Friction element composition

ABSTRACT

A friction binder for a friction element composition, especially useful where cashew nut shell oil and/or vegetable oils have been used in a phenolic resin composition, may be prepared by blending a non-oxylated resole with resin selected from the group consisting of an oxyalkylated resole, alkylated resole, an oxyalkylated novolac, an alkylated novolac, and mixtures thereof. The friction element composition is prepared by adding to this binder asbestos fiber and friction imparting materials, and curing the resultant material.

Grazen et a1.

FRICTION ELEMENT COMPOSITION Inventors: Frank S. Grazen; Melvin L.Buike;

Frank M. Bryzinsky, all of North Tonawanda, N.Y.

Hooker Chemicals & Plastics Corporation, Niagara Falls, N.Y. Filed: Dec.20, 1972 App]. No.: 317,035

Related U.S. Application Data Division of Ser. No. 188,596, Oct. 12,1971, Pat. No. 3,767,612, which is a continuation of Ser. No. 872,737,Oct. 30, 1969, abandoned.

Assignee:

U.S. Cl 260/38; 260/19 R; 260/19 A; 260/39 R; 260/399 B; 260/51.5;260/838; 260/840; 260/D1G. 39

Int. Cl C08g 37/18; C08g 51/10 Field of Search .1 260/838, 38, DIG. 39

References Cited UNITED STATES PATENTS 6/1944 Smith 260/838 5] Apr. 15,1975 2,570,513 10/1951 Bloch 260/838 2,684,351 7/1954 Williams 260/8382,741,651 4/1956 Been et a1 260/838 3,549,576 12/1970 Anderson et al.260/838 3,767,612 10/1973 Grazen et al. 260/838 Primary ExaminerJohn C.Bleutge Attorney, Agent, or FirmPeter F. Casella; James F. Mudd [57]ABSTRACT A friction binder for a friction element composition,especially useful where cashew nut shell oil and/or vegetable oils havebeen used in a phenolic resin composition, may be prepared by blending anon-oxylated resole with resin selected from the group consisting of anoxyalkylated resole, alkylated resole, an oxyalkylated novolac, analkylated novolac, and mixtures thereof. The friction elementcomposition is prepared by adding to this binder asbestos fiber andfriction imparting materials, and curing the resultant material.

5 Claims, No Drawings FRICTION ELEMENT COMPOSITION This is a division ofco-pending application SN 188,596, filed Oct. 12. 1971, now US. Pat. No.3,767,612. issued Oct. 23, 1973, which is a continuation of applicationSer. No. 872.737, filed Oct. 30, 1969, now abandoned.

This invention relates to a resinous material as a binder for frictionelements and more particularly to those elements which are suitable foruse in brakes of automotive vehicles. clutch facing, machine brakes andmany other industrial applications. It is especially useful where cashewnut shell oil polymerizates or vegetable oil-modified phenolic resincompositions have been used in the past.

Phenol aldehyde, or hydroxy aromatic-aldehyde condensation productshaving methylol side or end groups are known in the art as resoles Theyare formed from condensing a phenol with an excess of aldehyde and withan alkaline catalyst, also known as onestage" resins and are of thethermosetting type. Except when oxyalkylated, they are self setting.That is, upon the application of heat there results the formation of aresite. which is an infusible three-dimensional polymer.

Phenol aldehyde novolac resins, on the other hand, are phenol-endedchain polymers. They are formed by the reaction of an aldehyde with anexcess of phenol in the presence of an acid catalyst and/or heat. Theyare thermoplastic, permanently soluble and fusible. However, upon theaddition of a curing agent, they can be cured into an insoluble,infusible resin. Thus, novolac resins are known as two-stage" resins.

Phenol aldehyde condensation products have been used as binders forabrasive materials. However, to our knowledge, the novel phenol aldehydeproducts of this invention have not been used as binders.

As used herein friction particle" is intended to mean having theproperties of substantially no softening at elevated temperatures andwill not flow together or cohere with other particles, as a frictionbinder would, or fuse with like friction particles. It is insoluble,having an acetone extraction of less than 35 percent and often less than5 percent; it is infusible, i.e., has gone beyond the B stage. to the Cstage. It will not melt at 700F. A friction particle is held in placewith a friction binder.

As used herein, a friction binder" has the properties of flowability.and has adhesive and cohesive bonding action and thereby binds togetherthe asbestos and other additives (including a friction particle)necessary for building a brake lining or other similar article ofmanufacture. The binder, as supplied to the industry, will melt as a drypowder or is a liquid resin, and can be either an A stage or B stageresin. The binder becomes a C stage resin after it is combined with theother ingredients and cured.

The composition of the binder. friction particle and other additives, isheated to between 300400F. and pressed at between 500-2000 pounds persquare inch in order to form a brake lining composition, or clutchfacing or other braking device.

It has now been found that a composition of matter useful as a frictionbinder can be prepared by blending hydroxy aromatic hydrocarbonaldehyderesole with a resin selected from the group consisting of anoxyalkylated hydroxy aromatic hydrocarbon-aldehyde resole, an alkylatedhydroxy aromatic hydrocarbon-aldehyde resole, an alkylated hydroxyaromatic hydrocarbonaldehyde. an oxyalkylated hydroxy aromatichydrocarbonaldehyde novolac and mixtures thereof. The first said resolecan be alkylated but not oxyalkylated. Among the preferred embodimentsof this invention are the following:

1. The blended product of between about 5 and about 40 percent by weightof an oxyalkylated resole with between about and about 60 percent byweight of one or more of i a. one or more non-oxyalkylated,non-alkylated resoles,

b. a non-oxyalkylated, alkylated resole,

c. a mixture of a non-oxyalkylated resole and a nonoxyalkylated,non-alkylated resole,

d. a mixture of a non-oxyalkylated, non-alkylated resole and anon-oxyalkylated alkylated novolac, and

e. a mixture of a non-oxyalkylated, non-alkylated novolac and anon-oxyalkylated, non-alkylated resole.

2. The blended product of between about 95 and about 60 percent byweight ofa non-oxyalkylated, nonalkylated resole with between about 5and about 40 percent by weight of one or more of a. an oxyalkylatednovolac, and b.

oxyalkylated, alkylated resole.

3. The blended product of between about 5 and about 40 percent by weightof an oxyalkylated novolac with between about 95 and about 60 percent byweight of one or more of a. two or more non-oxyalkylated. non-alkylatedresoles,

b. an alkylated resole,

c. a mixture of an alkylated resole and a nonoxyalkylated, non-alkylatedresole.

d. a mixture of a non-oxyalkylated. non-alkylated resole and anon-oxyalkylated alkylated novolac, and

e. a mixture ofa non-oxyalkylated, non-alkylated resole and anon-oxyalkylated, non-alkylated novolac.

4. The blended product of between about 5 and about 95 percent by weightof a solid, B-stage nonoxyalkylated, alkylated resole, with betweenabout 95 and about 5 percent by weight of a liquid, A-stagenonoxyalkylated, alkylated resole.

In general. an oxyalkylated hydroxy aromatic material, whether it is anovolac or a resole, will not react with a novolac by itself. Themethylol groups on a resole are believed to be needed to react with thepolyol groups of the oxyalkylated materials.

The friction binder is formed by blending the resole with the novolac.or other resole. Usually, the resole and oxyalkylated resole oroxyalkylated novolac are both liquids, so blending is easily achieved.However, when one is a solid, it is powdered and mixed with the liquid.When both are solids, both are dry blended such as by ball millingtogether. Then they are mechanically blended, such as by being passedthrough a hammer mill equipped with a quarter mesh screen.

Normally, the materials are not reacted together. However, in somecases, it may be desirable to partially react the blended mixture toincrease its viscosity. The temperature chosen should be within thelimits of relatively easy reaction control and will normally be fromabout to 210F. The resultant material is normally in the A stage ofpolymerization. However, in some cases. the oxyalkylated resole oroxyalkylated novolac a nonin combination with a resole and a novolac isreacted and carried to a B stage condition. This reacted B stage blendcan be used by itself or in combination with a formaldehyde donor, suchas hexamethylenetetramine, as a binder. The blend is suitable for use asa friction com position constituent and as a binder for brake liningfillers.

Examples of phenols which can be used in preparing a phenol aldehyderesole or novolac for use in practicing the invention include ortho-,paradirecting hydroxy or amine aromatic compounds having 6 to 24 carbonatoms such as phenol itself (C,,H -,OH), naphthol, anthranol andsubstituted derivatives thereof where the substituents on the aromaticcompound are independently selected from H, Cl, Br. F. NH; and

a. alkyl groups or radicals of l to 60 carbon atoms, preferably of l to30 carbon atoms, and their various isomeric forms and substituted on thearomatic nucleus in the orthoor paraposition;

b. cycloalkyl groups of to 12 carbon atoms such as cyclohexyl,cyclopentyl, methylcyclohexyl, butylcyclohexyl, and the like.

c. alkyl, aryl and cycloalkyl ketonic groups wherein the hydrocarbonportion is as defined above in (a) and (1. alkyl, aryl and cycloalkylcarboxylic groups wherein the hydrocarbon part is defined as above in(a) and (b);

e. aryl groups of6 to 24 carbon atoms such as phenyl, naphthyl, anthryl,and the like;

f. aryl substituted alkyl wherein the aryl is phenyl which may containlower alkyl and/or hydroxy substituents so that the resulting hydroxyaromatic is, for exam ple, a bisphenol; and

g. mixtures of the aforesaid hydroxy aromatics.

Suitable substituted phenols include the following: para-phenyl phenol,para-benzyl phenol, para-betanaphthyl phenol, cetyl phenol,para-cumyl-phenol, para-tert-butyl phenol, sec-butyl phenol,para-tertamyl phenol, para-tert-hexyl phenol, para-alphanaphthyl phenol,para-hydroxyacetophenone, parahydroxybenzophenone, para-isooctyl phenol,para-tertoctyl phenol, para-cyclohexyl phenol, para-d-limonene phenol,para-l-limonene phenol, a phenol alkylated with oleic acid, such asphenol alkylated with oleic acid, para-decyl phenol. para-dodecylphenol, paratert-decyl phenol, butyl naphthol, amyl anthranol,para-nonyl phenol, para-methyl phenol, bisphenols such aspara,para-isopropylidene diphenol, para,para'- methylene diphenol, aswell as the corresponding 0rtho-derivatives of the previously mentionedcompounds such as ortho-butyl phenol and ortho-nonyl phenol as well asmixtures thereof, and aniline.

Mixtures of various hydroxy aromatic compounds mentioned herein also maybe used.

Included among the phenolic reactants which may be used are those knownas the cresylic acids and these often comprise a heterogeneous mixtureof having two reacting hydrogen positions on each of them; that is,compounds unsubstituted in the orthoand parapositions of the molecule,to compounds that only have one functional position, and hence,relatively unreactive. These compounds may include the following: 3,5-xylenol, m-cresol, 3,4-xylenol, 2,5-xylenol, 2,3-xylenol, phenol,p-cresol, orthocresol, 2,4-xylenol, and 2,6- xylenol. Cresylic acids ortar acids are generally applied to phenol and its homologs which mayinclude cresols,

xylenols, trimethyl phenols, ethyl phenols, and higher boiling materialssuch as dihydroxy phenols, polycyclic phenols and the like. They areoften obtained by a lowtemperature trimerization of coal, lighnite, andthe like, or a conventional high-temperature coke oven tar, or theliquid product of petroleum cracking both thermo and catalytic, shelloil, coal hydric hydrogenation products, and the like.

Polyhydroxy aromatic reactants, such as resorcinol, may also be used.

Particularly useful in this invention are mixtures of aniline and phenolto react with an aldehyde or ketone to produce either a novolac or aresole, depending on the other conditions described above.

Also useful in the invention are mixtures of urea and phenol to reactwith the aldehyde or ketone to produce either a novolac or a resoledepending on the other conditions described above.

Among the aldehydes which may be used within the scope of this inventionto produce either the resole or the novolac, are formaldehyde or any ofits variations, such as 37 percent formalin concentration orparaaldehyde, acetaldehyde, propionaldehyde, isobutyraldehyde,isopentaldehyde, and the like. The aldehyde should have not more than 8carbon atoms and should not detrimentally affect the resinification oroxyalkylation of the resin. Preferred aldehydes are those having from Ito 4 carbon atoms, such as formaldehyde, which may be in aqueoussolution (37 percent), or in any of its low polymeric forms such asparaform or trioxane. Other aldehydes include para-aldehydes, furfural,2- ethyl-hexanal, ethylbutyraldehyde, heptaldyde and glyoxal,benzaldehyde and crotonaldehyde.

Novolacs To prepare a novolac, the proportion of aldehyde to becondensed with the hydroxy aromatic compound may be varied in order toobtain different molecular weights, and the viscosity of the finishedresin may be controlled by the mole weight of the novolac; preferablythe proportion of aldehyde employed is from 0.5 to 1.0 per mole of thehydroxy aromatic compound.

Among the substituted phenols which may be used to prepare the novolacsfor this invention are those substituted with long-chain ethylenicallyunsaturated hydrocarbons, such as the linseed-type oils. However, it iswithin the scope of this invention to employ any animal and/or vegetableoil which achieves the objects of this invention based on the similarityin properties withthe long-chain hydrocarbon oils. Such oils would beposi-.

tioned on the phenol in the orthoor parapositions, and preferably in theparaposition. Many of them are similar in properties to linseed oilhaving nonconjugated unsaturation of at least 50 iodine number, and havesufficient compatibility with the novolac after it is polymerized.Safflower oil is typical of these oils. It may be in the form of aglycerol ester of the fatty acids wherein the fatty acids are of acomposition comprising more than 40 percent by weight of linolenic acid.The remaining percentages of fatty acid can be any saturated orethylenically unsaturated fatty acid having 12 to 22 carbon atoms andmore preferably oleic and linolenic acid so that the fatty esters havean iodine number of at least 50. The iodine value (iodine number) is ameasure of unsaturation, and is defined as the number of grams of iodinerequired per grams of unsaturated material to obtain the saturatedmaterial. In addition to the preferred glycerol ester, other polyhydricalcohols can be reacted with the described fatty acids to produce a lowacid number ester of a polyol having 2 or more hydroxyl groups. Typicalpolyols include ethylene glycol, diethylene glycol, pentaerythritol,dipentaerythritol, sorbitol and the other polyhydric alcohols.

The acid catalyst to be used when preparing the novolacs to be used inthis invention may be chosen from oxalic acid, sulfuric acid,hydrochloric acid and other strong acids used in the art for preparingnovolacs. In addition, wetting agents of the anionic type, such assodium alkylaryl sulfonates, are also useful as secondary catalysts inpreparing novolacs.

The two-stage resins are curable by reaction with hexamethylenetetramine to form dibenzyl and tribenzyl amines, as well ashexatriphenol. One may also use ammonium hydroxide, which reacts withthe formaldehyde to form hexamethylene tetramine. Other amines may alsobe used, such as ethylene diamine or ethylene triamine, or methylamines,etc. These can be used to react with formaldehyde to form a compositionsimilar to hexamethylene tetramine. The resulting compound would be analdehyde donor.

The phenol aldehyde novolac type resin is prepared by charging thedesired phenol and aldehyde raw materials and catalysts to a reactionvessel. The reactions begins at about 100C. and proceeds undertemperatures up to about 200C., at any pressure up to about 100lbs/square inch gauge for about one /2 hours, or until the desireddegree of polymerization has taken place. Thereafter, the catalyst isneutralized where necessary, and the excess reactant, water, and othermaterials are taken off by dehydration and the molten resin isdischarged from the vessel. It has been found that a novolac which hasnot been neutralized and is stable will cure more rapidly with a resolethan a novolac which has been neutralized.

From the foregoing, it is apparent that many hydroxy aromatic compoundsmay be used in practicing the present invention to provide a novolacwhich can be then reacted with an hydroxy aromatic aldehyde resole toform the friction particle of this invention, provided the aromatichydroxy] group is reactive and the hydroxy aromatic compound is capableof reacting with an aldehyde or a mixture of aldehydes to produce anovolac condensate. Pure, refined phenols may be used, but this is notnecessary. For instance, phenols may be alkylated and then may bereacted in crude form with an aldehyde. In such crude form, the phenolsmay contain some polyalkylated, as well as non-alkylated, pheonols.

The process for alkylation of a phenol is well-known in the art. First,dehydration (of water) is carried out with vacuum at elevatedtemperatures, for instance, between about 100 and about 150C. under avacuum of between about and about 30 inches of mercury. Then, thedehydrated phenolic material is acidified to a pH of between about 1 andabout 5 with H SO or in some cases BF Following this, a terpene orvegetable oil is added and the reaction mixture heated to between about80 and about 140C. at atmospheric pressure. The molar ratio of reactantsis between about 0.1 mole of terpene or vegetable oil per mole of phenolto about 2.5 mole of terpene or vegetable oil per mole of phenol.

when tung oil is employed as a vegetable oil in the alkylation, use ofBF;, to acidify would cause gelation, so it is not used, but H can beused.

The proportion of aldehyde to be condensed with the hydroxy aromaticcompound to form a precondensate may be varied to prepare novolacs ofdifferent molecular weights. Viscosity of the finished precondensate maybe controlled by the mole weight of the novolac. Preferably, theproportion of aldehyde employed varies from about 0.5 to 1.0 mole permole of phenol when a monoor difunctional phenol is used. In instanceswhere a trifunctional phenol is used, i.e., unsubstituted in theorthoand parapositions, a preferred upper limit of the aldehyde may beabout 0.70 mole of aldehyde per mole of phenol so as to minimize theformation of insoluble, infusible condensates. It is preferred that thealdehyde and phenol be condensed using an acid catalyst to shorten thetime required for complete condensation of the reactants. Suitable acidcatalysts include sulfuric acid, hydrochloric acid, and oxalic acid.These catalysts are generally employed in the amount of 0.1 to about 5percent by weight of phenol to be condensed.

Where a mixed aldehyde, phenolaldehyde precondensate is to be prepared,it is formulated by charging the desired phenol and aldehyde rawmaterials and catalysts to a reaction vessel. The reaction proceedsunder temperatures from about 25 to about 150C. at a pressure from aboutambient up to about 100 pounds per square inch gauge pressure for aperiod of time from about 5 minutes to about 5 hours, a suitable timebeing about one and one-half hours, or until the desired degree ofcondensation has taken place. The phenol is first reacted with thelonger-chain aldehyde to form a phenol-longer chain aldehydeprecondensate, followed by a second-step reaction of the phenol-longerchain aldehyde precondensate with formaldehyde to form a thermosettablephenol aldehyde precondensate material. In the second step, thereactants are refluxed at atmospheric pressure, although higher refluxtemperatures up to about 150C. can be used by employing elevatedpressure. The formaldehyde can be added all at once in the second step,or added gradually. If the formaldehyde is added all at once, then atemperature range between about 50 and about C. is used at the beginningof the second-step reaction, until the exothermic reaction subsides, andthen the temperature is increased slowly to between about and about C.

and held until further exothermic reaction subsides, and then thereaction mixture is heated to reflux temperature which is about C. atatmospheric pressure. If elevated pressure is used, then the refluxtemperature can be increased to as high as about C. If the formaldehydeis added gradually in the second step, then a temperature range betweenabout 95 and about 140C. can be used. The catalyst is then neutralizedand the excess reactant, water and other materials are taken off.

While the precondensate is still at an elevated temperature, from about25 to about C., but below the boiling point of the resultant solution orsupension, with about 100C. being very suitable, it may be reduced inviscosity by addition of suitable solvent. The amount of solvent mayvary from about 10 to 70 percent of the precondensate by weight and asuitable ratio of precondensate to solvent is about 10 parts ofprecondensate to 9 parts of solvent. The controlling factor is theresulting viscosity of the precondensate prepared, rather than theactual volume of solvent charged. Among the solvents which may be usedfor this purpose are ethanol, methanol, toluene, xylene, ketones, suchas acetone, and methylethyl ketone, and mixtures of aromatic andaliphatic hydrocarbons, such as mixtures of benzene and mineral spirits,or benzene and acetone.

Oxyalkylation Oxyalkylated resins are prepared'which preferably containsubstantially no free reactive hydroxy aromatic groups, for example,less than about 0.5 percent of the aromatic hydroxyl present originallyin the hydroxy aromatic or hydroxy aromatic aldehyde condensate. Toremove the aromatic hydroxys, the hydroxy aromatic aldehyde resin can bereacted with a compound which etherifies the aromatic hydroxyl groups sothat almost all of the aromatic hydroxy groups present in each hydroxyaromatic aldehyde condensate unit are so reacted.

The preferred method of hydroxyalkylation is by reaction with compoundscontaining a mono-oxirane ring. Such compounds include ethylene oxide,propylene oxide, butylene oxide, styrene oxide and cyclohexene oxide,glycidol and epichlorohydrin. Many other monoepoxides can be used, butthe alkylene oxides containing not more than 6 carbons are generallypreferred. Additional useful compounds are phenyl glycidyl ether andrelated compounds prepared from the reaction of epichlorohydrin andmonofunctional alkylated and halogenated phenols such aspentaehlorophenyl glycidyl ether.

Catalysts for the reaction of the oxirane ring compounds and phenolichydroxyl groups may be alkali or alkaline earth hydroxides, primaryamines, secondary amines, tertiary amines or basic alkali salts. Theseinclude sodium, potassium, lithium, calcium and barium hydroxides,amines such as methyl, dimethyl, diethyl, trimethyl, triethyl,tripropyl, dimethyl benzyl, dimethyl hydroxyethyl,dimethyI-Z-hydroxypropyl and the like, and salts of strong bases andweak acids such as sodium acetate and benzoate.

The reaction may be carried out at temperatures of about roomtemperature to 250C., and preferably in the absence of solvents,although solvents may be used to reduce viscosity when desired. Whenoxyalkylating resoles, the reaction should be carried out at lowertemperatures than when oxyalkylating novolacs, because there is apossibility that reaction of the methylol groups with other methylolgroups gives methylene linkages, formaldehyde and gelation. Whenoxyalkylating a novolac, temperatures between room temperature and about200C. can be used. When oxyalkylating a resole, temperatures betweenroom temperature and about 100C. may be used.

The aromatic hydroxyalkylated by reacting alkylene halohydrins with thearomatic hydroxyl using equivalent amounts of an alkali metal hydroxideto bring about the reaction. Suitable alkylene halohydrins are ethylenechloroand bromohydrins, propylene chloroand bromohydrins, 2,3-butylenechloroand bromohydrins, and glyceryl chloroand bromohydrins.

Another method for hydroxyalkylating novolacs is reaction with alkylenecarbonates such as ethylene carbonate and propylenecarbonate, using acatalyst such as potassium carbonate.

At least one mole of alkylene oxide or other etherifying or esterifyingagent is required per mole of aromatic hydroxyl. However, resinsprepared by reaction with up to 7 moles of alkylene oxides per mole ofphenolic hydroxyl have been found to be useful.

Resoles The liquid one-stage resin (resole) which forms a part of thisinvention may be formed by reacting an hydroxy aromatic compound with anexcess of formaldehyde in alkali such as sodium hydroxide dissolved inwater. The reaction mixture is gradually heated to reflux and held atreflux until less than about 1 percent of free formaldehyde remains.This provides a preferred reaction product which has less than 2 percentof the formaldehyde unreacted, although this is not critical in thisprocess.

Less than 2 percent free CH O is desirable. The reaction mixture is thencooled and the catalyst neutralized with some acid such as glacialacetic acid and the pH is adjusted to roughly 6 to 7.5. The reactionmixture may be then further reacted with hexamethylene tetramine or someother aldehyde donor, i.e., curing agent. The resin is then dehydratedto between about 50 to 95 percent solids, and preferably between about81 to 85 percent solids.

The alkaline catalyst used in preparing the resoles to v be used in thisinvention may be any of those known in the art; for instance, sodiumhydroxide and calcium hydroxide. In general, the alkali metal hydroxidesand the alkaline earth metal hydroxides and ammonium hydroxide and theamines such as triethanol amines may be used.

Following the intercondensation reaction to form a resole, astoichiometric quantity of a strong acid such as sulfuric acid,hydrochloric acid, phosphoric acid or oxalic acid, or the like, is addedto the reaction mixture in order to neutralize the alkaline condensationcatalyst. Sulfuric acid is conveniently employed to neutralize a sodiumhydroxide catalyst. The alkaline catalyst may also be neutralized bydilution through repeated washing, however, it is preferred to use anacid. The final resin should have a pH between about 5.5 and 7.5 forgood stability.

The hydroxy aromatic compound employed in a resole can be alkylated, ifdesired, with alkyl groups containing 1 to 12 carbon atoms, or withunsaturated groups, including the long-chain unsaturated vegetable oranimal oils, to form alkylated hydroxy aromatic compounds that whenreacted with an aldehyde form heat reactive resoles. These includealkylene groups of 2 to 36 carbon atoms, fatty acids, polyethers, alkylethers, polyesters and polyols and mixtures of these.

Among the high molecular weight or polymeric materials containingaliphatic carbon-to-carbon unsaturation, there are included suchnaturally occurring materials as unsaturated vegetable, fish or animaloils such as linseed, soya, tung, sesame, sunflower, cotton seed,herring, menhaden, and sardine oils, etc., or chemically modifiednaturally occurring materials such as allyl ethers of starch, cellulose,or acrylate esters thereof, etc., synthetic drying oils, polymersobtained by polyetherification of such unsaturated compounds such asmaleic, fumaric, itaconic, aconitic, chloromaleic, dimerized fattyacids, anhydrides or acids from allyl glycerol, methallyl glycerolether, glycerol monoacrylate, butene diol, pentene diol, or polymersobtained by polyetherification of the unsaturated polyols. Other oilsinclude castor oil, tall oil, oiticica oil, safflower oil. and the like,oleic and linolenic acids. These fatty acids have from 12 to 22 carbonatoms. They are often in combination as a glycerol ester or incombination with other polyhydric alcohols or polyols such as ethyleneglycol, diethylene glycol, pentaerythritol, dipentaerythritol, sorbitol,and the. like polyhydric alcohols.

The blending of the resole with the other components in accordance withthis invention can be in various proportions depending upon the ultimateproperties desired in the friction binder to be produced, but willgenerally be in the range of about 50 to about 95 weight percent of thenon-Oxyalkylated resole based on the total weight of resin components.

It is to be understood that the Oxyalkylated resole or oxyalkylatednovolac described herein will not be a friction binder alone unlessblended with a nonoxyalkylated, non-alkylated resole resin or with anonoxyalkylated. alkylated resole resin. The Oxyalkylated resole produceis a liquid and will not cure. The preferred compositions of theinvention contain at least one of an Oxyalkylated resole and anOxyalkylated novolac in combination with the non-Oxyalkylated resole.

The friction binder of this invention may be used I alone or with otherfriction binder materials known in the art.

A typical friction element contains about 30 to 60 weight percentasbestos fiber. up to 40 weight percent other inorganic filler andabrasives, about to 15 percent organic filler and about [5 to about 30weight percent binder, including the binder of this invention; allpercents are by weight of total composition. Asbestos fiber, abrasivematerials and filler materials are charged into a mixer followed by theaddition of the binder. The components are kneaded until the fiber,abrasives, and any fillers are thoroughly wetted and a uniform mass isobtained. The mass is discharged from the mixer, rolled out into sheetsor extruded or pressure molded and dried. after which it is ready forfurther processing into friction elements. When the blend is in a Bstage condition of polymerization, and powdered, it is mixed with theasbestos and other additives, pressed together in a hot moldingoperation at approximately 1000 psi. at a mold temperature from about300350F. and then cured.

The abrasives, that is, the friction imparting agents and fillersemployed within the scope of this invention include, but are not limitedto brass chips, metal shavings and filings, silica, talc, wood flour,chalk, clay, mica, fiber glass, felt, carbon black, graphite metalnitrides and oxides, ground cashew nut shell oil polymerizate, and thefriction particle disclosed in Ser. No. 872,753 filed Oct. 30, 1969, nowU.S. Pat. No. 3,658,751. These abrasives and fillers can be used toachieve the particular amount of bulk and coefficient of frictiondesired. The above listed materials have a particle size such that theywill pass through a U.S. Standard Sieve (1940) No. 3 which has a sieveopening of 6.3 millimeters. Preferably, the particle size of thesematerials will range from passing through a No. 4 sieve, sieve openingsize 4.76 millimeters, and yet be retained on a No. 100 sieve, sieveopening size 0.140 millimeter.

The following Examples are given to further illustrate the invention.Unless otherwise indicated, all parts are by weight and temperatures indegrees centigrade.

EXAMPLE 1 PART A (The Resole) A reaction vessel is charged with 100parts of phenol, 120 parts of formalin (37 percent formaldehyde) and 2parts of flake caustic dissolved in 4 parts of water. This reactionmixture is heated gradually to 60C. and held at 60C. until there is lessthan 3 percent free formaldehyde and cooled to 30C., after which 5.5parts of lactic acid diluted with 5.5 parts of water is added whichneutralizes this composition to a pH of 5.5-6.5. After the pH range isachieved, the resin is dehydrated to 59-63 percent solids and cooled toroom temperature. The resultant product is a low viscosity liquid, andis identified in Table 11 as resin Rd.

PART B (The Oxyalkylated Novolac) The Oxyalkylated novolac can also bereferred to as a polyol of a novolac which is oxyethylated, using fromabout one mole to about 7 moles of ethylene oxide to 1 mole of phenol,depending on the properties desired. For this Example, a resin was usedwith a ratio of 2 moles of ethylene oxide to 1 mole of phenol.

A typical modified phenol-aldehyde condensation product is prepared byintroducing 3,000 parts phenol. 13 parts of oxalic acid catalyst and 6parts of a wetting agent of Nacconol (sodium alkylaryl sulfonate) into ajacketed reactor and heating to 100C. (The anionic wetting agents ofalkylaryl sulfonate type are preferred.) Then 1,1 10 parts of a 37percent aqueous formaldehyde solution are added to the reactor at a ratethat the heat of reaction provides a vigorous reflux. Refluxing iscontinued for 2 hours after the completion of the formalin addition. Thereactor contents are dehydrated at 180C. and then dephenolated at 200C.at millimeters vacuum. Approximately 2,030 parts of phenol-aldehydecondensate are produced. Then 7.2 parts of sodium hydroxide areintroduced to the reactor. Ethylene oxide is then added to the reactoras either a vapor or a liquid. The reactor temperature is maintained at190C. for the initial 2 hours and is then permitted to increase to therange of 200 to 220C. until the addition of 878 parts of ethylene oxideis complete. The resulting condensation product had a hydroxyl number of370, and a Gardner viscosity at 50C. of about 2,000 seconds, and isidentified as resin Nc in Table 111.

A novel friction binder of the invention was made by blending 60 partsof Part A with 40 parts of Part B. The friction binder was used informulating a mixture comprising parts of dry mix, and 0.6 part water asfollows. The dry mix was composed of 62.5 parts by weight of asbestosshorts, Quebec Standard Asbestos Grade 7K, 12.5 parts by weight ofCardolite friction particles, and 25 parts of barytes abrasive filler.The moisture content of the dry mix was held low between 0:75 and 1.0percent to avoid any possibility of blistering of the element duringcure.

The dry mix was charged to an internal mixer equipped with a Sigma-typeblade. The dry materials were mixed and blended for 5 minutes. Then 20parts of the above-described friction binder were added and mixed for 1hour until the mass was uniform. The dough-like mix was then dischargedfrom the mixer and charged to an extruder. The extruder was equippedwith a 2 by A inch rectangular die and had an applied ram pressure of to300 pounds per square inch.

The dough-like mix was then extruded in a shape which TABLE II-Continuedwas satisfactory for brake linings. The extruded linings R l R F l fwere oven dried for 16 hours at 120F. The linings were Resin 8 cm a thencut to proper length, reheated for 2 to 3 minutes a b c* d at about325F., bent or arched to the desired curva- 5 Raw Material ture andplaced into forms (i.e., molds) for curing. These linings were thencured for 8 hours at about pflmTcni-ary m 311,0 350F. The cured liningsafter cooling were expanded P Sulfuric Acid 2.76 to the proper size formounting into brake shoes. The Wutcr 3777 333 resulting frictionelements were found to be satisfacl0 glen 1 A 21-31 0 H tory for use onautomobile brakes. A 1 Triethvlamine l.76 EXAMPLE 2 Lactic Acid 2.12

70 parts of Part A and parts of Part B of Example In Resole Rc thephenol. formaldehyde. and 2.5 parts of triethylaniinc were 1 wereb]ended The resulting friction binder was then first reacted. Thisproduct was then oxypropylated with the remaining specified cd'e s madeup into a brake lining by adding sufficient my 1 m amounts of the resinblend to give parts of solid resin TABLE [[1 after curing, 50 partsasbestos fibers, 10 parts Cardolite friction particle, and 20 partsbarytes abrasive filler. Nommc Resin Fmmulmions The resulting mix wasextruded to form a drum-type 20 Resin I h c brake lining, which was thendried for 16 hours at RuwMmcrial 120F. and cured for 8 hours at 350F.The cured brake Phenol 58.45 45.85 lining was tested and found to haveRockwell hard Formaldehyde (372%) 4062 2292 M98 ness of 33M at roomtemperature which is satisfactory p Teniury octyi p no 73,95 incommercial practice. The lining was heated at g 9 MZF Y Sulfmwte -8;8-22 500F. for 15 minutes and had retained a Rockwell u 5; hardness of43L. indicating that the composition re- Ammoniacol Liquor 2.31 00tained strength and hardness at elevated temperature. ggs s g z EthyleneOxide 36.68 EXAMPLES 3 to 15 3O Maleic Anhydride The procedure ofExample 2 was repeated to produce additional drum-type brake liningsusing various proportions of resoles and novolacs for which the for-EXAMPLE 16 mulations are shown in Tables 11 and 111. In Table 1 3000parts of asbestos fiber, 750 parts barytes abraare shown the proportionsof the indicat d resins us d sive filler, 250 parts of Cardolitefriction particle and to make the resin binders, the Rockwell hardnessesof 1000 arts of the resin binder of Example 2 were mixed the cured brakelinings as prepared and after heating at in a sigma blade mixer toproduce a granular mixture. 500F. for 15 minutes. The resulting mixturewas charged into a mold and cold TABLE I Rockwell Hardness ExampleResole Novolac Oxyalkylation Resin of Brake Lining Number FormulationFormulation Formulation Ratio After l5 minutes As Prepared at 500F.

1 Rd Nc 60/40 76M 20L 2 Rd Nc 70/30 33M 43L 3 Rd Rc 70/30 56M l3M 4 RaRc 70/30 22R 34.! 5 Ra-Rd Rc 35/35/30 27M 21L 6 Ra-Rd /50 30M 36L 7 RdNb Rc /20/20 62L 54R 8 Ra Nc /30 21R 60] 9 Ra-Rd Nc 35/35/30 36M l8L H)Rd Na Nc 60/10/30 78M 38L 1 1 Rd Nb Nc 60/10/30 12M 25L 12 Rat Na 80/2067L 81R l3 Ra-Rb 90/10 l4 Ra Nb 90/10 l5 Ra-Rd Nb 45/45/10 63L R TABLEI] pressed at 1000-3000 pounds per square inch to form a disc brake pad.The molded pad was stripped from Resole Resin Formulation 60 the moldand cured in a circulating air oven by raising Resin the temperaturegradually from room temperature to Raw Material 3 b c d 350F. over aperiod of 8 hours, followed by holding the temperature at 350F. for 8hours. Phenol l9.93 24.43 42.37 Formaldehyde 29.00 24.45 43.98 50.84EXAMPLE 1? (37.27:) Alcohol 28.90 65 The procedure of Example 15 wasrepeated except 53% that the friction particle was prepared inaccordance Phenol with Example 2 of copending application Ser. No. q872,753, filed on even date herewith now US. Pat. No. Oxal|c Acid 0.02

Various changes and modifications can be made in the products of thisinvention without departing from the spirit and scope thereof. Thevarious embodiments of the invention disclosed herein serve to furtherillustrate the invention but are not intended to limit it.

We claim:

1. A friction element composition, comprising a friction impartingabrasive agent, an inorganic filler and a binder composition consistingessentially of a nonhydroxyalkylated hydroxy aromatichydrocarbonaldehyde resole containing substantially no etherifiedaromatic hydroxy groups and at least about percent by weight of adifferent alkylated hydroxy aromatic hydrocarbon-aldehyde resole,wherein the alkylated groups are substituted on the aromatic ring andare selected from the group consisting of:

a. alkyl groups of l to 60 carbon atoms,

b. cycloalkyl groups of 5 to 12 carbon atoms,

c. alkyl, aryl and cycloalkyl ketonic groups wherein the hydrocarbonportion is as defined in (a) and d. alkyl, aryl and cycloalkylcarboxylic groups wherein the hydrocarbon portion is as defined in a de. aryl groups of 6 to 24 carbon atoms, and

f. aryl substituted alkyl wherein the aryl is phenyl,

lower alkyl-substituted phenyl or hydroxy substituted phenyl.

2. The composition of claim 1 comprising from about 95 to about 60percent by weight of a nonhydroxyalkylated, non-alkylated resole withfrom about 5 to about 40 percent by weight of a nonhydroxyalkylated,alkylated resole.

3. The composition of claim 1 wherein the first said resole is thecondensation produce of phenol and formaldehyde in an alkaline medium.

4. The composition of claim 1 comprising from about 5 to about percentby weight of a B-stage nonhydroxyalkylated alkylated resole with fromabout 95 to about 5 percent by weight of an A-stage,nonhydroxyalklylated, alkylated resole.

5. A friction element composition comprising about 30 to about 60 weightpercent asbestos fiber, up to about 55 weight percent of other fillersand friction imparting abrasive agents and about 15 to about 30 weightpercent of a binder composition consisting essentially of anon-hydroxyalkylated hydroxy aromatic hydrocarbon-aldehyde resolecontaining substantially no etherified aromatic hydroxyl groups and atleast about 5 percent of a different alkylated hydroxy aromatichydrocarbon-aldehyde resole, wherein the alkylated groups aresubstituted on the aromatic ring and are selected from the groupconsisting of:

a. alkyl groups of l to 60 carbon atoms,

b. cycloalkyl groups of 5 to 12 carbon atoms,

0. alkyl, aryl and cycloalkyl ketonic groups wherein the hydrocarbonportion is as defined in (a) and (b),

d. alkyl, aryl and cycloalkyl carboxylic groups wherein the hydrocarbonportion is as defined in n e. aryl groups of 6 to 24 carbon atoms, and

f. aryl substituted alkyl wherein the aryl is phenyl,

lower alkyl-substituted phenyl or hydroxy substituted phenyl.

1. A FRICTION ELEMENT COMPOSITION, COMPRISING A FRICTION IMPARTINGABRASIVE AGENT, AN INORGANIC FILLER AND A BINDER COMPOSITION CONSISTINGESSENTIALLY OF A NON-HYDROXYALKYLATED HYDROXY AROMATICHYDROCARBON-ALDEHYDE RESOLE CONTAINING SUBSTANTIALLY NO ETHERIFIEDAROMATIC HYDROXY GROUPS AND AT LEAST ABOUT 5 PERCENT BY WEIGHT OF ADIFFERENT ALKYLATED HYDROXY AROMATIC HYDROCARBON-ALDEHYDE RESOLE,WHEREIN THE ALKYLATED GROUPS ARE SUBSTITUTED ON THE AROMATIC RING ANDARE SELECTED FROM THE GROUP CONSISTING OF: A. ALKYL GROUPS OF 1 TO 60CARBON ATOMS, B. CYCLOALKYL GROUPS OF 5 TO 12 CARBON ATOMS, C. ALKYL,ARYL AND CYCLOALKYL KETONIC GROUPS WHEREIN THE HYDROCARBON PORTON IS ASDEFINED IN (A) AND (B) D. ALKYL, ARYL AND CYCLOALKYL CARBOXYLIC GROUPSWHEREIN THE HYDROCARBON PORTION IS AS DEFINED IN (A) AND (B), E. ARYLGROUPS OF 6 TO 24 CARBON ATOMS, AND F. ARYL SUBSTITUTED ALKYL WHEREINTHE ARYL IS PHENYL, LOWER ALKYL-SUBSTITUTED PHENYL OR HYDROXYSUBSTITUTED PHENYL.
 2. The composition of claim 1 comprising from about95 to about 60 percent by weight of a non-hydroxyalkylated,non-alkylated resole with from about 5 to about 40 percent by weight ofa non-hydroxyalkylated, alkylated resole.
 3. The composition of claim 1wherein the first said resole is the condensation produce of phenol andformaldehyde in an alkaline medium.
 4. The composition of claim 1comprising from about 5 to about 95 percent by weight of a B-stagenon-hydroxyalkylated alkylated resole with from about 95 to about 5perceNt by weight of an A-stage, non-hydroxyalklylated, alkylatedresole.
 5. A friction element composition comprising about 30 to about60 weight percent asbestos fiber, up to about 55 weight percent of otherfillers and friction imparting abrasive agents and about 15 to about 30weight percent of a binder composition consisting essentially of anon-hydroxyalkylated hydroxy aromatic hydrocarbon-aldehyde resolecontaining substantially no etherified aromatic hydroxyl groups and atleast about 5 percent of a different alkylated hydroxy aromatichydrocarbon-aldehyde resole, wherein the alkylated groups aresubstituted on the aromatic ring and are selected from the groupconsisting of: a. alkyl groups of 1 to 60 carbon atoms, b. cycloalkylgroups of 5 to 12 carbon atoms, c. alkyl, aryl and cycloalkyl ketonicgroups wherein the hydrocarbon portion is as defined in (a) and (b), d.alkyl, aryl and cycloalkyl carboxylic groups wherein the hydrocarbonportion is as defined in (a) and (b), e. aryl groups of 6 to 24 carbonatoms, and f. aryl substituted alkyl wherein the aryl is phenyl, loweralkyl-substituted phenyl or hydroxy substituted phenyl.